Japanese Unexamined Patent Publication Nos. 2005-247992 and 2004-250574 describe gasification systems capable of generating a pyrolysis gas from biomass materials. Japanese Unexamined Patent Publication No. 2005-247992 describes a “Biomass Gasification System and Operating Method Therefor” wherein a gas reforming tower is connected to a supply system which delivers fuel gas generated from biomass in a gasifire, the gas reforming tower having the purpose of raising the temperature of the fuel gas to a process temperature at which the tar component in the fuel gas may be thermally cracked. A gas cooling tower is installed downstream from the gas reforming tower as means of cooling the fuel gas. Moreover, the remaining char generated in the gasifire is used as a fuel for a thermal airflow generator which generates thermal energy utilized by the gasifire.
Japanese Unexamined Patent Publication No. 2004-250574 discloses a “Method for Modeling Fixed Bed Gasifier for Biomass” which describes a biomass gasification process utilizing a down-draft type of a fixed bed gasification furnace.
Japanese Unexamined Patent Publication No. 2004-250574 discloses a so-called downdraft furnace which has certain operational limitations requiring that the biomass materials fed into the furnace not to be a fibrous substance such as bamboo or tree bark, not to be of varying size, and not to contain excess amounts of water. This type of furnace places various restrictions on the process because it is not able to gasify biomass materials of various types, size, and water content. Moreover, a further ramification of this type of furnace is that it is difficult to control at will the gasification temperature therein.
Japanese Unexamined Patent Publication No. 2005-247992 discloses a rotary kiln which applies indirect heating to generate a pyrolysis gas from biomass. Due to the large tar component contained in the pyrolysis gas, the gas reforming tower must be installed downstream from the rotary kiln as means of removing the tar component. Moreover, the gas cooling tower must also be provided due to the 1,100° C. temperature of the pyrolysis gas exiting the gas reforming tower. The installation of these apparatuses results in a gasification system of extraordinarily large size.
It could therefore be helpful to provide a compactly structured biomass gasification apparatus capable of gasifying a wide range of biomass materials regardless of their size and/or water content, and of removing a high percentage of the tar component generated in a gasification process.